1. Field of the Invention
The present invention relates to a disk loading device for an optical disk player, for example, a compact disk player or a digital video disk player, and more particularly to a disk tray shifting device wherein a loading motor for shifting the disk tray is installed movably along the cross direction of a main base, so that the device becomes to be compact and the reliability of power transmission thereof is improved.
2. Description of the Prior Art
Conventional optical disk player includes a disk tray for accommodating a disk, and a pickup for reading datum recorded on the disk. A conventional optical disk player also includes a disk loading device including a loading motor for shifting the disk tray from the outside of the player body to the inside thereof or from the inside of said body to the outside thereof is mounted on one end of the main base, and a pickup driving motor for sliding the pickup, is mounted on the other end of the main base.
In the conventional disk loading device as described above, generally, a rack portion is formed on the underside of the disk tray, and a pinion to be rotated by the driving force transmitted from the loading motor is engaged with said rack portion. By this engagement between the rack portion and the pinion, the relative motion of the disk toward a turntable mounted on the pickup base is performed, so that the loading operation or the unloading operation is accomplished. Hereinafter, the structure and the operation of the conventional disk tray shifting device will be described in detail with the appended drawings, FIG. 1 through FIG. 3.
FIG. 1 is a perspective view showing an external appearance of an optical disk player, FIG. 2 is a schematic top view showing a disk tray shifting device of said player, and FIG. 3 is a schematic front view of said disk tray shifting device, In the conventional disk tray shifting device as shown in FIG. 1 through FIG. 3, a loading motor 2 is mounted on one end of the front portion of a main base installed inside a player body 20, and the driving force of said motor 2 is transmitted to a idler gear 7 through a pulley 4 mounted on the upper end of said motor 2, a belt 3 and a gear train. Said gear train consists of a first gear 5 and a second gear 6, and said idler gear 7 includes a pinion 7a on the upper portion thereof, wherein the pinion 7a is formed integrally with said idler gear 7.
Referring to FIG. 2 and FIG. 3, an L-shape arm 9 is inserted pivotably on the shaft 8 of the second gear 6, the idler gear 7 is inserted rotatably on the shaft 9a formed on the first end portion 9b of said arm 9, and a guide protrusion 10 is projected from underside of the second end portion 9c. On the lower end of said shaft 8, a cylindrical cam 11 having a cam groove 11a engraved on the surface thereof is fixedly mounted, and the lower end of said guide protrusion 10 is inserted into a dimple 11d formed on the upper surface of said cam 11 through a curved shape guide slit 12. Said guide slit 12 is formed on the main base 1.
On the other hand, on the underside of a disk tray 13, there is provided with a rack portion 14 along the longitudinal direction of said tray 13, and said rack portion 14 is engaged with the pinion 7a formed integrally with the idler gear 7. Said rack portion consists of a linear shape rack portion 14a and a curved shape rack portion 14b. 
In FIG. 3, the reference number 15 indicates a protrusion, which is formed on the front end of an up-down pivoting base (not shown) and inserted to the cam groove 11a of said cam 11. Said up-down pivoting base is pivotably mounted on the main base 1, and supports one side of the pickup base not shown in FIGS. 1-3.
Now the loading operation of said disk tray shifting device will be described.
Firstly, when the disk tray 13 is shifted outwards from the inside of the player, the disk D is placed on said tray 13. Thereafter, if the loading signal is applied to the disk tray shifting device, the loading motor 2 becomes to be actuated so that the pulley 4 mounted on the shaft of said motor 2 is rotated clockwise. At this time, since the driving force of said motor 2 is transmitted to the pinion 7a through the belt 3, the first gear 5, the second gear 6 and the idler gear 7, said pinion 7a engaged with the rack portion 14 is rotated clockwise, so that the disk tray 13 is shifted to the loading position. That is, when the pinion 7a is rotated clockwise by the driving force transmitted from the loading motor 2, the disk tray 13 having the rack portion engaged with said pinion 7a is shifted along the arrow direction, as shown in FIG. 2. Such shifting operation of the disk tray 13 is finished when the end portion of said linear shape rack portion 14a reaches said pinion 7a. Thereafter, when said tray 13 is shifted, the operation for placing the disk D on the turntable is continued.
When the shift operation of said tray 13 is finished, if the pinion 7a continues to rotate, the arm 9 is rotated counterclockwise on the shaft 8 by the rotation of said pinion 7a, and said pinion 7a is moved along the curved shape rack portion 14b. Thus, the guide protrusion projected from the underside of the second end portion 9c of said arm 9 is also moved counterclockwise along the guide slit 12.
At this time, the cam 11 is rotated on the shaft 8 because the lower end of said guide protrusion 10 is inserted into a dimple 11d formed on the upper surface of said cam 11. Accordingly, the protrusion 15, which is formed on the front end of the up-down pivoting base and placed in the first position 11b of the cam groove 11a, is moved along the said cam groove 11a and becomes towards the second position 11c of said cam groove 11a. Therefore, the pickup base is moved upwards, and the disk D placed on the tray 13 is loaded on the turntable of the spindle motor, not shown. Here, said first position 11b of said groove 11a indicates the position of said protrusion 15 when the center hole of the disk D is not inserted on the shaft of the turntable, and said second position of said cam groove 11a indicates the position of said protrusion 15 when the center hole of the disk D is inserted on the shaft of the turntable.
The unloading operation of said disk tray shifting device is performed according to the reverse order of said loading operation.
However, since the loading motor is mounted fixedly on one side of the main base in the above described conventional disk tray shifting device, a large number of components are necessary in order to the power transmission from the loading motor to the pinion. And since the rotating radius of the idler gear and the space occupied with the belt are large, it is necessary to provide a large space for mounting said idler gear and said belt. Therefore, there are problems in miniaturization of said power transmission means and in the accuracy of the power transmission.
In addition, although not shown in FIGS. 1-3, it is necessary to provided separate locking device in order to prevent the tray from moving freely after loading operation in the conventional disk tray shifting device. However, the need for such a separate device also inhibits the miniaturization of said shifting device.
It is, an object of the present invention to provide a new type disk tray shifting device for the optical disk player in which a loading motor for shifting the disk tray with respect to a turntable is mounted movably in the cross direction of a main base in order to minimize the installation space of components.
Another object of the present invention is to provide a disk tray shifting device which can transmit the driving force of the loading motor to the disk tray by minimizing power transmission stages so as to control the shifting operation of said disk tray precisely.
A further object of the present invention is to provide a disk tray shifting device which is compactly and simply constructed by installing the loading motor and the power transmission means in a single bracket and by minimizing the installation gap between components.
Another object of the present invention is to provide a disk tray shifting device which is able to improve the assembling workability and to interchange the components easily by the compaction.
Still another object of the present invention is to provide a disk tray shifting device in which a locking device for preventing the tray from moving freely after loading operation is formed on said bracket so as to accomplish loading operation and locking operation simultaneously.
A further object of the present invention is to provide a disk tray shifting device in which the upward movement of a pickup base and the crosswise movement of the loading motor can be accomplished together.
Another object of the present invention is to provide a disk tray shifting device wherein a cable for supplying electrical signals to the loading motor can be easily connected without any interference between other components.
Still another object of the present invention is to provide a disk tray shifting device wherein a sensor for detecting the position of the loading motor is simply constructed, and yet wherein a signal transmission assembly for supplying electrical signals to a spindle motor and the like is compactly and simply connected.
These objects are achieved according to the present invention by providing a disk tray shifting device which is arranged in the optical disk player, and which comprises: a main base; a guide bar arranged on said main base along the cross direction of said main base; a bracket mounted slidably on said guide bar and being moved along said guide bar, wherein said bracket includes a guide groove on one side thereof; a loading motor attached to the bottom of said bracket; a tray including a rack portion formed on the underside thereof; a power transmission device installed on said bracket and transmitting the driving force of said loading motor to said tray, wherein said power transmission device consists of a intermediate gear and a idler gear; and a circuit portion mounted on one side of said main base.
In the present invention, said rack portion formed on the underside of the tray includes a longitudinal rack formed along the longitudinal direction of said tray and a lateral rack formed along the cross direction of said tray. Therefore, when a pinion projected from the upper surface of the idler gear is engaged with said longitudinal rack and that pinion begins to rotate, the tray is shifted along the longitudinal direction of the main base. Furthermore, when said pinion is engaged with said lateral rack and that pinion begins to rotate, the bracket is moved along the guide bar in the cross direction of the main base.
When said bracket is moved along the guide bar, an up-down pivoting base supporting one side of a pickup base is pivoted on the shaft upwards or downwards. Thus, a turntable mounted on said pickup base is either inserted into the center hole of the disk, or removed from said center hole.
And when said bracket is moved along the cross direction of the main base, a locking device formed on said bracket is put into contact with a stopper formed on the underside of the tray in order to prevent the tray from moving freely.
In addition, said circuit portion and said loading motor are interconnected with the signal transmission assembly and said circuit portion includes a sensor for detecting the position of said bracket.